Richard,

I'll test it fully tonight and post the results. I have been dumping powdered stabilized shock into the hot tub regularly because it seemed to get the CL up quicker and because I was trying to get at least a little CYA into the tub. Bleach doesn't seem to get the levels up as high as bleachcalc would suggest that it should. I also salted the water up to 2000PPM (I think!) I will check that as well.

My tub is outdoors, but covered 24/7 except when we are in it.

My disdain is that there appears to be sooo little margin for error. It seems to go from 5+PPM CL to nothing in a day! I used to get the rash regularly with Bromine as well. I am just suprised that Baquacil seemed to be so much more effective at killing off Pseudomonas aeruginosa.